"Dallas Buyers Club" and "Gravity" may be the darlings among critics as we look forward to another awards season, but the film at this year's Toronto International Film Festival with possibly the highest number of collective past Oscar wins is "August: Osage County," thanks to the powerhouse ensemble cast led by Meryl Streep and Julia Roberts.

But becoming a squabbling mother-daughter duo was far from the inaugural Streep-Roberts onscreen union the 45-year-old "Pretty Woman" actress had always envisioned. "To work with Meryl Streep is a dream come true for anyone. To know her is an honor," said Roberts at the film's press conference at TIFF. "She is such a beautiful person and it was intimidating, certainly, to be in these scenes with her. Choking her, and things like that, were not how I pictured it going in my mind all these years. I thought we'd be together, having tea and speaking in fabulous accents all dressed up. But there we were ... I'm sweating and have on a big butt pad. So that's not how it was in my dream."

Watch Exclusive Trailer Premiere for 'August: Osage County':

"August: Osage County" is based on the acclaimed play by Tracy Letts, which won the Pulitzer Prize for Drama in 2008. Perhaps the dysfunctional family drama to end all dysfunctional family dramas — and a slightly kinder, gentler story (well, relatively, anyway) from the playwright who brought us "Killer Joe" and "Bug" — "August" tells the tale of the sprawling Weston clan as a family crisis brings them back to the Oklahoma house in which they grew up. The story focuses mostly on the Weston sisters — Barbara (Roberts), Ivy (Julianne Nicholson) and Karen (Juliette Lewis) — and their fiery relationship with their mother, Violet (Streep), a domineering matriarch who now suffers from mouth cancer.

The impressive, sizable cast also includes Benedict Cumberbatch, Dermot Mulroney, Abigail Breslin, Ewan McGregor and — in something of a meta-nod to who might've been Letts' main influence in writing the play — Sam Shepard as the missing Weston patriarch. "I think I cut off Dermot [Mulroney]'s circulation just squeezing his hand with excitement and thrill to see what everybody did — because it's such a great ensemble," Roberts said at the recent gathering of cast and press in Toronto. "Even though there were a lot of scenes that we are all in together, my favorite is the bus station scene with Benedict [Cumberbatch] and Chris [Cooper]. It was my favorite scene in the play and it was my favorite scene when I read the screenplay."

The trailer showcases what looks to be a tour de force performance by Streep as a hard-drinking, highly opinionated alpha female who can effortlessly drive anyone around her stark raving mad — including her brother-in-law Charlie, played by her "Adaptation" co-star Chris Cooper. And despite the tension — and occasional violence (!) — between their two characters, Roberts found working with the three-time Oscar winner to be a treat ... even if the details of the particular gig that brought them together weren't quite what the "Erin Brockovich" star had in mind for their first collaboration.

"She doesn't just snap her fingers and be a genius," Roberts explained of Streep. "She really is just the hardest working girl in the room. I was so grateful to see that up close."

Despite the strangling and the butt pad, the big juicy human drama at the center of it all made it a richly rewarding experience for Roberts.

"However, it was still amazing," said the "August" actress. "I think that at the end of every day — coming out of the truth of the Weston family and into our own truths of who we are together with a hug and a kiss and an 'I love you' — that was really the elixir that I needed to come in the next day and climb over the next table to choke her in the next way."

"August: Osage County" had its TIFF premiere earlier this week and will open in U.S. theaters on December 25.